Half of all adult Americans now own either a tablet computer or a smartphone, and one-third use their mobile devices to view news stories and video clips at least once a week.

That's according to a survey by the Pew Research Center's Project for Excellence in Journalism, which polled more than 9,500 adults from late June to early August.

The findings have "major implications for how news will be consumed and paid for," says Pew. About 20 percent of the mobile news users surveyed said they paid for an online subscription in the last year.

But mobile viewing doesn't necessarily mean that people are cutting back on viewing news on PCs or in newspapers. About half of the tablet news users that Pew surveyed say their tablets spur them to spend more time consuming news, and about one-third say they get news from new sources they didn't use before. Nearly one-third of the mobile users also have print-only subscriptions, and most have no plans to give them up.

Devices based on Google Inc.'s Android platform are gaining momentum. Pew found that just over half of tablet owners reported owning Apple's iPad, compared with 81 percent a year ago. Forty-eight percent now own an Android-based device, including Amazon.com Inc.'s Kindle Fire.